Boil the potatoes and carrots in salted water (boil for about 15 minutes after it starts boiling). Clean every top of broccoli and cut it in half. Briefly stew kale until tender. Cut the cooked potatoes into cubes and carrots into strips. Unite all the ingredients for the dressing in a bowl and mix them well. Mix broccoli with other vegetables, pour the sauce and sprinkle with fresh arugula. This dish is best served hot, immediately after preparation. Make dressing with 1 large spoon of mustard, 2 tablespoons of olive oil and 2-3 tablespoons of lemon juice.